[jira] [Comment Edited] (HDFS-9902) dfs.datanode.du.reserved should be difference between StorageType DISK and RAM_DISK

["Arpit Agarwal (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-9902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15260434#comment-15260434 ] 

Arpit Agarwal edited comment on HDFS-9902 at 4/27/16 4:31 PM:
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Hi [~brahmareddy], thank you for reporting this. The fix lgtm.

The unit test can be done more simply without MiniDFSCluster. Just instantiate "FsVolumeImpl" objects with different storage types and check {{#reserved}} is initialized correctly. Also could you please update the documentation of {{dfs.datanode.du.reserved}}?


was (Author: arpitagarwal):
Hi [~brahmareddy], thank you for reporting this. The fix lgtm.

The unit test can be done more simply without MiniDFSCluster. Just instantiate "FsVolumeImpl" objects with different storage types and check that the value of {{#reserved}}. Also could you please update the documentation of {{dfs.datanode.du.reserved}}?

> dfs.datanode.du.reserved should be difference between StorageType DISK and RAM_DISK
> -----------------------------------------------------------------------------------
>
>                 Key: HDFS-9902
>                 URL: https://issues.apache.org/jira/browse/HDFS-9902
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: datanode
>    Affects Versions: 2.7.2
>            Reporter: Pan Yuxuan
>            Assignee: Brahma Reddy Battula
>         Attachments: HDFS-9902-02.patch, HDFS-9902.patch
>
>
> Now Hadoop support different storage type for DISK, SSD, ARCHIVE and RAM_DISK, but they share one configuration dfs.datanode.du.reserved.
> The DISK size may be several TB and the RAM_DISK size may be only several tens of GB.
> The problem is that when I configure DISK and RAM_DISK (tmpfs) in the same DN, and I set  dfs.datanode.du.reserved values 10GB, this will waste a lot of RAM_DISK size. 
> Since the usage of RAM_DISK can be 100%, so I don't want dfs.datanode.du.reserved configured for DISK impacts the usage of tmpfs.
> So can we make a new configuration for RAM_DISK or just skip this configuration for RAM_DISK?



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